Another highly entertaining thread! I assume that each of us dreams a great deal, maybe every night/or whenever we are accustomed to sleep? As for myself, I rarely remember my dreams and I have always observed that, unless I make a conscious effort to actually remember the details of a dream, it soon vanishes from my mind as opposed to a "real" waking experience which generally does not. I assume that one of the functions of dreaming is to "purge" the mind of thoughts/feelings which are perhaps unhelpful or maybe upsetting...a kind of therapy, and that it does this very effectively, hence blanking it from our waking memory, I find unfortunately that some rather good dreams are also lost to recall, (which is a trifle unfair if you ask me!) Perhaps we all experience/react to dreams slightly differently, which might render the efforts of those hoping to make generalised observations rather pointless or at best merely generalisations. I have certainly had the experience of friends or family members recounting to me details of quite vivid dreams they have had only to find that years later if the dream comes up in conversation with that same person, they have no recollection of it, this I have taken to confirm my hypothesis of the mind's "purging"...but that's just a suggestion..with dreams who knows??
Neither would I discount the possibility that dreams may provide a glimpse into the past/future or some parallel dimension, the accounts by XBergMann, escargot and the particularly moving and powerful post from PeteS are truly fascinating! I have often experienced a sense of a different, yet familiar reality when I dream, a sense of "recognition"...as in "here I am again...I know this place..the rules are different here to the other place" Amongst fragments of the dreams which I can recall are some truly strange juxtapositions, an example being that, in a recent dream I was wandering about in Knaresborough (a nearby town in Yorkshire, UK) and yet I round a corner and there is a landscape with huge (alpine sized or bigger) snow topped mountains reaching beyond the clouds, it's quite a shock, but somehow I "knew" that these mountains were there..in my dream...it was somehow "familiar".
I can also identify with, and have experienced those dreams where elements from recent experience, or even a TV show can show up but what has always fascinated me are those dreams which are just so absolutely strange that I can find no clue as to how they came into being. I'm not referencing bizarre Salvador Dali dreamscapes or the apparitions and zombies of popular horror...no, these are dreams which are (in some cases) more commonplace, but "wrong" in a much more subtle way and which (for me at least) makes them infinitely more disturbing. I had a dream a month or so ago which was particularly disturbing. I am not disposed to describe it for two principal reasons, firstly.....I hope to forget it and writing it down would render this impossible...there would always be a trace of the horror! and secondly, it would probably not strike any reader as being particularly disturbing at all..perhaps they would just find it odd (I think that which is truly disturbing is that which is unique to the experiencer..."made to measure" if you prefer.
With regard to the intriguing functioning of memory as described by catseye, I am inclined to suggest that this singular "forgetfulness" may not be confined to the realm of dreams. Very recently I was revisiting some of my own song ideas/musical compositions imported to my PC from an old hard disk drive (to me still quite new technology!) To my surprise...(and quite a pleasant surprise...I think like most musicians/songwriters, I find my own output rather unsurprising and not particularly enjoyable to listen back to) I found several songs/ pieces of music which I had completely forgotten...song titles which meant nothing to me...of course I did remember them once I started playing them back, but honestly I could have lost them forever and been none the wiser. I'm really glad I "rediscovered" them!